Therefore, high-quality randomized controlled trials are still needed for a better understanding of the effects of these 2 popular interventions. Moreover, no study has directly compared the effectiveness of these 2 methods for patients with chronic low back pain. Therefore, the objective of this randomized controlled trial was to compare the effectiveness of the Back School and McKenzie methods in patients with chronic nonspecific low back pain for the outcomes of pain intensity, disability, quality of life, and range of motion.